Simplify the following expression: $\sqrt{250} - \sqrt{40}$
First, try to factor any perfect squares out of the radicals. $= \sqrt{250} - \sqrt{40}$ $= \sqrt{25 \cdot 10} - \sqrt{4 \cdot 10}$ Separate the radicals and simplify. $= \sqrt{25} \cdot \sqrt{10} - \sqrt{4} \cdot \sqrt{10}$ $= 5\sqrt{10} - 2\sqrt{10}$ Finally, simplify by combining the terms. $= ( 5 - 2 )\sqrt{10} = 3\sqrt{10}$